Method and device for automatically determining heart valve damage

ABSTRACT

A method and device for automatically detecting heart valve damage for four heart valves are proposed. The automatic determination method makes use of three or more heart tone microphones to simultaneously record heart tones of a patient&#39;s heart, and then separates the heart tones into four heart tone signals of the aortic valve, the pulmonary valve, the tricuspid valve and the mitral valve of the heart based on the timing characteristics and related techniques. Next, these four heart tone signals are digitally processed into sampling signals. Subsequently, the convolution method is used to process the sampling signals for producing system transfer functions. Finally, the system transfer functions and the reference database are compared to verify and determine damage for the four heart valves. The automatic determination method can judge heart valve damage to enhance the quality and convenience of medical treatment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. application Ser. No. 11/060,437, filed Feb.18, 2005, which claimed Priority from Taiwanese application No.93132247, filed Oct. 22, 2004, the entire disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for automatically determiningheart valve damage and a device for performing the same and, moreparticularly, to a method and device for automatically determining andjudging heart valve damage.

2. Description of Related Art

The heart is an important organ of the human body, and operates all thetime. A heart with a small problem badly affects the health of the humanbody. A clear description of the heart is difficult because it is a verycomplicated organ. Therefore, the measurement of heart tones is stillthe most common method used by doctors in clinical diagnosis of theheart status.

The heart pulsation results in flow and circulation of the blood. Therewill be changes in tissue form and fluid mechanics during the pulsationperiod. Sounds emitted due to these changes can be heard by using astethoscope. These sounds are called heart tones. Heart murmurs arecaused by turbulent flow of the blood. They can be divided into thesystolic period, the diastolic period and the sustaining periodaccording to the occurrence time. They can also be divided into theaortic valve, the pulmonary valve, the tricuspid valve and the mitralvalve according to the diagnosis positions. A valve is like a door forcontrolling the blood to flow in a certain direction. For instance, theaortic valve is located between the left ventricle and the main artery,and controls the blood supply of the whole human body. For a patientwith a narrow aortic valve, there will be a pressure difference betweenthe left ventricle and the main artery when the heart contracts. Thenarrower the aortic valve, the larger the pressure difference. A doctorcan thus find the heart murmur of the systolic period.

The heart tones can be divided into a first heart tone, a second hearttone, a third tone and a fourth heart tone. The first heart tone occursat the initial stage when the heart contracts, and includes twocomponents caused by the closure of the mitral valve and the tricuspidvalve. The second heart tone occurs at the last phase when the heartcontracts, and also includes two components caused by the aortic valveand the pulmonary valve. The third heart tone occurs at the initialstage when the heart expands. The fourth heart tone occurs at the lastphase when the heart expands. The first and second heart tones aresounds generated when the valves close and are thus easy to observe. Thethird and fourth heart tones are less apparent and thus difficult toobserve. Abnormal sounds, sounds other than these four heart tones, areviewed as heart murmurs. These heart murmurs represent symptoms of heartdiseases including valve stenosis, valve regurgitation, valve cracks, orother defects in structure.

Therefore, the heart tone diagnosis is an important tool for a doctor todetermine the heart status. A series of stethoscopes have been developedto help doctors determine the heart status. For example, the US. Pat.App. No. 20030072457 discloses an electronic stethoscope, which providesthree operation modes. The first operation mode only filters out thephysiologic sounds of the heart. The second operation mode only filtersout the physiologic sounds of the lung. The third operation modeenhances the observation of abnormal heart tones through comparison ofnormal and abnormal heart tones at different amplification ratios. Thiselectronic stethoscope, however, does not automatically help the doctorsanalyze the damage of heart valves.

U.S. Pat. No. 4,619,268 discloses an esophageal stethoscope and vitalsigns monitoring system, which can discriminate the heartbeat sounds andbreath sounds of the lung and then calculate out the heartbeat rate andthe breath rate of the lung for monitoring the vital signs of a patient.This esophageal stethoscope and vital signs monitoring system, however,also does not automatically help the doctors analyze the damage of heartvalves.

The above conventional stethoscopes can't automatically help the doctorsto analyze the damage of heart valves. The determination of heart tonesstill depends on the subjective judgment of a doctor, and is thussubject to environmental and artificial influences such as the doctor'sage, hearing sensitivity, and the training degree of the auscultationskill. This problem may cause erroneous judgment of the damage of theheart valves.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an automaticdetermination method and device of the damage of heart valves to enhancethe quality and convenience of medical treatment.

To achieve the above object, the present invention provides an automaticdetermination method of the damage of heart valves. This methodcomprises the following steps. First, a reference database, which storesrelationship data between accumulated clinical damages of heart valvesand heart tones for assisting in analysis and judgment, is installed inadvance. Three or more heart tone microphones are then used to pick upand record heart tones. Next, the heart tones are separated into fourheart tone signals of the aortic valve, the pulmonary valve, thetricuspid valve and the mitral valve of the heart based on the timingcharacteristics and related techniques. Subsequently, these separatedheart tone signals are digitally processed into sampling signals.Convolution is then performed to operate the sampling signals to producesystem transfer functions. Finally, the system transfer functions of theheart valves are separately compared with the built-in referencedatabase to verify and determine the damage of the four heart valves.

The present invention also provides an automatic determination method ofthe damage of heart valves. This device comprises a reference database,heart tone microphones, a heart tones separating unit, a heart tonesignal digital processing unit, a convolution unit, a comparison unitand a display. The reference database is used for storing relationshipdata between accumulated clinic damages of heart valves and heart tones.The heart tone microphones are used for recording heart tones. The hearttones separating unit is connected with the heart tone microphones andused to separate the heart tones into four heart tone signals of theaortic valve, the pulmonary valve, the tricuspid valve and the mitralvalve of the heart based on the timing characteristics and relatedtechniques. The heart tone signal digital processing unit is connectedwith the heart tones separating unit and used to process the separatedheart tone signals of the heart valves into sampling signals. Theconvolution unit is connected with the heart tone signal digitalprocessing unit and used to process the sampling signals for producingsystem transfer function through the convolution method. The comparisonunit is connected with the convolution unit and the reference databaseand used to compare separately the system transfer functions of the fourheart valves to know the damages of the four heart valves. The displayis connected with the comparison unit and used to display the damage ofthe heart valves.

BRIEF DESCRIPTION OF THE DRAWINGS

The various objects and advantages of the present invention will be morereadily understood from the following detailed description when read inconjunction with the appended drawing, in which:

FIG. 1 is a flowchart of an automatic determination method of the damageof heart valves of the present invention;

FIG. 2 is a block diagram of an automatic determination device of thedamage of heart valves of the present invention;

FIG. 3A is a diagram showing the positions of the aortic valve, thepulmonary valve, the tricuspid valve and the mitral valve of the heartsystem; and

FIG. 3B is a diagram showing the measurement positions of heart tones inthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, an automatic determination method of the damage ofheart valves of the present invention comprises the following steps.First, a reference database is installed in advance (Step S100). Thereference database stores relationship data between accumulated clinicdamages of heart valves and heart tones. Three or more heart tonemicrophones are simultaneously used to pick up and record heart tones,or the heart tones are separately measured at the aortic valve, thepulmonary valve, the tricuspid valve and the mitral valve of the heart(Step S102). Next, the heart tones are separated into four heart tonesignals of the aortic valve, the pulmonary valve, the tricuspid valveand the mitral valve of the heart based on the timing characteristicsand related techniques (Step S104). In one embodiment of the presentinvention, the heart tone signals can be obtained by subtracting theheart tone measured at the pulmonary valve from the heart tone measuredat the aortic valve, subtracting the heart tone measured at the aorticvalve from the heart tone measured at the pulmonary valve, subtractingthe heart tone measured at the tricuspid valve from the heart tonemeasured at the mitral valve, and subtracting the heart tone measured atthe mitral valve from the heart tone measured at the tricuspid valve.The heart tone signals can also be obtained in other ways of operations.

Subsequently, these separated heart tone signals are digitally processedinto sampling signals (Step S106). The convolution method is then usedto process the sampling signals to produce system transfer functions(Step S108). These system transfer functions are calculated out by usingthe impulse responses. That is, an input impulse and the heart tonesignals are convoluted to get the system transfer functions. Finally,the system transfer functions of the heart valves are separatelycompared with the built reference database to verify and determine thedamage of the four heart valves (Step S110).

As shown in FIG. 2, an automatic determination device of the damage ofheart valves of the present invention comprises a heart tone microphone30 for separately recording heart tones or three or more heart tonemicrophones 30 for simultaneously recording the heart tones at theaortic valve, the pulmonary valve, the tricuspid valve and the mitralvalve of the heart. FIG. 3A shows the positions of the aortic valve 52,the pulmonary valve 50, the tricuspid valve 54 and the mitral valve 56.FIG. 3B is a diagram showing the measurement positions of heart tones atthe aortic valve 52, the pulmonary valve 50, the tricuspid valve 54 andthe mitral valve 56.

The automatic determination device also comprises a signal processingsystem 44, which is connected with the heart tone microphones 30 andused for digital processing of the heart tones recorded by the three ormore heart tone microphone and operation and comparison of systemtransfer functions. The system processing system 44 comprises areference database 40 and a heart tones separating unit 32. Thereference database 40 is used to store relationship data betweenaccumulated clinical damage of heart valves and heart tones. The hearttones separating unit 32 is connected with the heart tone microphonesand used to separate the heart tones recorded by the three or more hearttone microphones 30 into heart tone signals of the aortic valve, thepulmonary valve, the tricuspid valve and the mitral valve of the heartbased on the timing characteristics and related techniques.

The heart tone signals of the heart valves can be obtained bysubtracting the heart tone measured at the pulmonary valve from theheart tone measured at the aortic valve, subtracting the heart tonemeasured at the aortic valve from the heart tone measured at thepulmonary valve, subtracting the heart tone measured at the tricuspidvalve from the heart tone measured at the mitral valve, and subtractingthe heart tone measured at the mitral valve from the heart tone measuredat the tricuspid valve. The heart tone signals can also be obtained inother ways of operations.

The automatic determination device of the damage of heart valves of thepresent invention further comprises a heart tone signal digitalprocessing unit 34, a convolution unit 36, a comparison unit 38 and adisplay 42. The heart tone signal digital processing unit 34 isconnected with the heart tones separating unit 32 and used to processthe separated heart tone signals of the heart valves into samplingsignals. The convolution unit 36 is connected with the heart tone signaldigital processing unit 34 and used to process the sampling signals forproducing system transfer function through the convolution method. Thecomparison unit 38 is connected with the convolution unit 36 and thereference database 40 and used to separately compare the system transferfunctions of the four heart valves with the built reference database 40to automatically determine the damages of the four heart valves. Thedisplay 42 is connected with the comparison unit 38 and used to displaythe damage of the heart valves.

Although the present invention has been described with reference to thepreferred embodiment thereof, it will be understood that the inventionis not limited to the details thereof. Various substitutions andmodifications have been suggested in the foregoing description, andother will occur to those of ordinary skill in the art. Therefore, allsuch substitutions and modifications are intended to be embraced withinthe scope of the invention as defined in the appended claims.

1. A method for automatically determining heart valve damage, comprisingthe steps of: installing a reference database for storing relationshipdata between accumulated clinical damage of heart valves and heart tonesin advance; using heart tone microphones to pick up and record hearttones; separating said heart tones into four heart tone signals of theaortic valve, the pulmonary valve, the tricuspid valve and the mitralvalve of the heart based on the timing characteristics and relatedtechniques; digitally processing said separated heart tone signals intosampling signals; making use of a convolution method to manipulate saidsampling signals for producing system transfer functions; and separatelycomparing said system transfer functions of said heart valves with saidreference database to verify and determine damage of said four heartvalves.
 2. The method for automatically determining heart valve damageas claimed in claim 1, wherein three or more said heart tone microphonesare used to pick up and record simultaneously said heart tones.
 3. Themethod for automatically determining heart valve damage as claimed inclaim 1, wherein said heart tones are separated into four heart tonesignals of the heart valves based on the timing characteristics, and theheart tone signals are obtained by subtracting the heart tone measuredat the pulmonary valve from the heart tone measured at the aortic valve,subtracting the heart tone measured at the aortic valve from the hearttone measured at the pulmonary valve, subtracting the heart tonemeasured at the tricuspid valve from the heart tone measured at themitral valve, and subtracting the heart tone measured at the mitralvalve from the heart tone measured at the tricuspid valve.
 4. The methodfor automatically determining heart valve damage as claimed in claim 1,wherein impulse responses are used to calculate said system transferfunctions.